A facile label-free electrochemiluminescence biosensor for target protein specific recognition based on the controlled-release delivery system

This paper described a novel label-free electrochemiluminescence assay for target protein based on a controlled delivery system. Iron oxide magnetic mesoporous silica nanocontainers were prepared by using a general procedure. The prepared magnetic mesoporous silica nanocontainers were applied to load the guest molecules [Ru(bpy)3]2+. Aptamers were used as gatekeepers on the pore outlets of the nanocontainers. In the presence of target proteins, the specific aptamer-protein interactions were employed as triggers for uncapping the pores and releasing the guest molecules from the nanocontainers. The amount of the guest molecule [Ru(bpy)3]2+ released from the magnetic mesoporous silica nanocontainers was monitored by the electrochemiluminescence assay. The results show that the releasing amount of [Ru(bpy)3]2+ is proportional to the thrombin concentration in the range of 0.6 pM-0.8 nM with a detection limit of 0.5 pM (S/N=3). The present work demonstrates that the fabricated nanocontainer using aptamer as the cap is a highly sensitive and selective key-in lock gating system for the label-free ECL biosensor.